The present invention relates to a fast breeder reactor, and more particularly to a fast breeder reactor which is suitable for incorporating therein a compact core structure.
A fast breeder reactor employs sodium, which is a liquid metal, as coolant and plutonium as fuel. The core of a fast breeder reactor is loaded with core fuel assemblies and blanket fuel assemblies. Each control rod is connected to a control rod driving mechanism, and vertically moves in a control rod guide pipe which is installed among fuel assemblies loaded in the reactor core. The output of the fast breeder reactor is controlled by control rods moved into and out of the reactor core. The core fuel assemblies, blanket fuel assemblies, and control rod guide pipes are supported by means of a core-supporting plate. Below the core-supporting plate, there is a high-pressure plenum into which high-pressure sodium delivered from a main circulating pump flows. The sodium in the high-pressure plenum flows into each fuel assembly through transverse holes of the entrance nozzle provided at the lower portion of each fuel assembly. The supply of sodium into control rod guide pipes can also be effected in a manner similar to that for fuel asemblies.